1. Field
Example embodiments relate to oxide semiconductor thin film transistors (TFT) and methods of manufacturing an oxide semiconductor thin film transistor (TFT). Other example embodiments relate to zinc oxide (ZnO) based semiconductor thin film transistors (TFT) and methods of manufacturing a zinc oxide (ZnO) based semiconductor TFT.
2. Description of the Related Art
A thin film transistor (TFT) using a semiconductor thin film may be applied to various fields. For example, a TFT is frequently used as an active device of a flat panel display device. An oxide semiconductor (e.g., a ZnO based semiconductor film) may be manufactured in a substantially low temperature process. A GaInZnO (GIZO) semiconductor may be amorphous. As such, a substantially large surface device may be manufactured using GIZO. A ZnO based semiconductor film may have a substantially high mobility. A ZnO may have desirable electrical characteristics like a poly-crystalline silicon.
The carrier density of a ZnO based semiconductor film may be sensitive to changes in oxygen content. The electrical characteristics of the ZnO based semiconductor may fluctuate due to thermal and/or chemical impact. If a channel is exposed to plasma during the manufacturing of a ZnO based thin film transistor, the channel may be damaged. The channel may be damaged by plasma having a substantially large amount of energy that is used for patterning a source and a drain. The damage may undesirably increase the carrier density on a surface of the channel. The increase in carrier density may cause a shift in a threshold voltage of the thin film transistor. The shifted threshold voltage may have a substantially large negative value. As such, a leakage current may be generated between the source and the drain even if a gate voltage is 0 V.